1. Field of the Invention
This invention relates to the field of drain plugs and more particularly, those plugs used while conducting pressure tests on plumbing systems.
2. Prior Art
On newly constructed plumbing systems, it is desired to plug all drains with a stopper. The drains include the waste drain and overflow drains of bathtubs. The drains are plugged for a variety of reasons but two major reasons are first to prevent waste material generated by construction from entering the drains and second to allow pressure testing of the plumbing system. The pressure test is typically required during a building department inspection. The pressure test consists of plugging all drains with stoppers and filling the pipes of the plumbing system with water. The waste drain and overflow drain are usually coupled to the same pipe but must be plugged individually to provide a seal. The drains are plugged and the pipes remain filled with water for an extended period of time while a building inspection takes place. During the test, vent pipes extending from the drain are typically filled with water to a level of 10 feet above the level of the drains.
The prior art method of blocking the drains is to place a dollar plug in the waste assembly and a plastic plug, dollar plug or Jim cap in the overflow assembly.
A dollar plug is illustrated in FIG. 1 and consists of a large rubber "accordian" washer sandwiched between two large metal washers. A threaded bolt extends through the washers and is secured by a wingnut.
A plastic plug simply fits inside of the drain to create a pressure seal and a Jim cap is comprised of a rubber plug with an outer sleeve. The plug fits into a pipe with the sleeve extending over the pipe.
A major disadvantage of dollar plugs and other prior art plugs is their tendency to blow out under pressure during the testing of the plumbing system. Since the plugs rely only on friction between the side wall of the drain and the rubber washer to form a seal, any water pressure of sufficient force to overcome that friction will cause the plug to fail or "blow out".
A second disadvantage of the dollar plug is their tendency to scratch and scar the finish of the drain. This is primarily due to the construction of the dollar plug which exposes metal parts to contact with the finish of the drain. As shown in FIG. 1, the upper metal washer extends over the rubber washer. This metal will come in contact with the finish of the drain, marring and scratching the surface.
Third, when plastic plugs, Jim caps or dollar plugs are used to plug the overflow assembly, an additional trip is required after the inspection test to install the overflow shoe and trim. This involves considerable labor cost.
It is an object of the present invention to provide a drain plug which will not blow out during the pressure testing.
It is another object of the present invention to provide a plug with no metal to finish contact when properly installed.
Yet another object of the present invention is to provide a drain plug which allows a one trip connection of the waste and overflow assembly.